Rotary hammer



Aug. 13, `1929. N. P. RIDGWAY ROTARY HAMMER Filed Feb. 4, 1925 INVENTOR NELSON R -/oa wny lIlI-Illllll Il/'llllllll/lllll4 Patented i3, L.

narran sie-iras NELSON P. RIDGWAY, F TACOMA, WASHINGTON.

ROTARY iraniana.

Application filed February This invention relates to rotary hammers and the principal object of the invention is to improve upon hammers of that character disclosed in the patent on rotary hammers issued to me on February 18, 1917 under Patent N o. 1,216,166; the improvement being in the provision of means for limiting the outward travel of the hammers in their guides and also in the provision of air cushions: for

lo checking the rebound of the hammer elements after they have struck the tool'used l1n the device.

In accomplishing these and other objects of the invention, I have provided the im- 15 proved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein- Figure 1 is a side view of a hammer enibodying the present invention; a side of the 20 housing being removed and parts being shown in section for better illustration.

Figure 2 is a horizontal, sectional view taken on the line 2 2 in Figure 1.

Figure 3 is a sectional view taken on line 3-3 in Figure 1.

Figure t is a view showing an end elevation of one of the hammer guides and retaining spring for limiting outward travel of the hammer elements in the guide.

Referring more in detail to the drawingsl designates an enclosing housing made up of opposite side sections 2 and 3 that are joined together by means of bolts 4 extended through the peripheries of the sections and a ring 5 interposed therebetween.

At one side of the casing is an extension 6 in which a tubular bushing 7 is fixed by a set screw 8 5 the bushing slidably containing the shank 9 of a riveting tool or other instrument 10 that may be operated by the striking of blows in rapid succession against its inner end.

Extended centrally through the housing is an operating shaft 11 supported rotatably by ball bearings 12 operating between collars 1313 that are formed or fixed on the shaft and annular bearings 14--14 that are fixed respectively to the opposite housing sections 2 and 3. Driving connection may be made with either end of the shaft by any suitable means such as a iiexible shaft.

Fixed on the shaft, in a plane that is perpendicular thereto and centrally between the sides of the housing is a plate 15 of rectangu- 4., 1925. sei-iai No. 6,758.

lar form, forming the hammer body, and fixed in. parallel relation to opposite edges of this plate are tubular guides 16 in which hammer elements 17 are slidably contained.

During operation of the device, the hammer n elements arecaused, by centrifugal force, to slide tothe outer ends of the carriers into position that they Will be brought into contact with the inner end of the shank of the tool 10 to effect the hammering operation.

The guides are so disposed that their axial l lines and the axial line of the shank will coincide at the time of impact of the hammer Y element with the shank.

To limit the outward movement of the hammer elements in their guides, I have provided the leaf springs 18 which are disposed against the ends of the hammer body and which have ends fixed thereto by clamping members 19 leaving the other ends free and disposed in overlapping relation with the outer ends of the guides to provide yieldable stops against which the hammer element engage to limit their outward movement. In the preferred construction, I use two leaf springs for each stop, one of which terminates closely adjacent the edge of the guide and the otherbeing provided with spaced apart fingers 21-21, as shown in Figure 4, which overlap the end of the hammer elements but which are sufliciently spaced so as not to interfere with direct impact of the shank with the hammers.

The inner end of each of the guides 16 is closed Aby a cap 25 which provides an air chamber 28 at the inner end of each hammer element. he rebound of the hammer elements upon striking the tool is cushioned by the air trapped in these chambers 26. Each cap is provided with a ball chamber 27 having air ports 28 at their outer ends and at their inner ends opening directly into the chambers 26. Contained within said chambers 27 are ball checks 29 which operate to close the ports 28 by the outward rush of air incidental to inward movement of the hammer elements upon striking the tool.

Closing of the ports provides the air cushion which 'checks the rebound. In order that part of the air may escape and will not act to drive the elements outwardly, I have provided small ports 80 opening outwardly from -the ball chambers as shown in Figure 1.

As a precaution, to check the rebound of the hammer elements in the event the balls 29 should stick or fail to close the ports 28, I have placed short, coiled springs 34 in the inner` ends of the guide cylinders. These are not ordinarily required and are held in place by being hooked to the ball retaining bars across the base of the chambers 27.

With the device so constructed the noise of operation is greatly reduced and a better operating and more satisfactory tool is provided.

Handles of a suitable'character may be provided for holding the hammer when in use and these may be fixed either to the casing as is indicated at 35 in Figure l or may be mounted about the driving shaft.

Having thus described my invention, what I claim as new therein and desire to secure by Letters-Patent, is:

l. In a device of the character described, a rotating hammer body, a tubular carrier fixed to the body, a hammer element slidably fitted in said carrier and extending` from the outer end thereof, yieldable means engageable with the outer end of the hammer element for limiting the outward travell of the element and a cap closing the inner end of the carrier to form an air chamber and having ports opening thereinto, one of which is relatively small; and a ball check mounted to close the larger of said ports against the discharge or' air therethrough and a rebound spring disposed within the inner end of the carrier.

2. In a device of the character described, a rotating hammer body, a tubular carrier iixed to said body, a hammer element slidably itted in said carrier and extending from the outer end thereof; a valved cap closing the inner end of said carrier to provide an air cushion for cushioning the rebound of the hammer element and a leaf spring fixed to the hammer body with one end overlapping the outer end of the carrier to yieldably limit the outward travel of the hammer element and a rebound spring disposed'within the inner end of the carrier.

Signed at Tacoma, Pierce County, Washington, this 15th day of December, 1924.

NELSON P. RIDGFWAY.V 

